1. Field of the Invention
This invention relates to communications terminals, and in one particularly preferred embodiment to mobile communications terminals, such as a mobile telephone for example.
2. Summary of the Related Art
One previously proposed communications terminal, in this case a mobile telephone, is illustrated schematically in FIG. 1 of the accompanying drawings.
As shown, the terminal 1 comprises a display 3, an aerial 5 and a plurality of keys 9 arranged in a keypad. The keys, as is known in the art, can be arranged as so-called hard keys with one predetermined function or alternatively they can be arranged as soft-keys which have a plurality of functions depending on the particular operating mode of the terminal. The terminal 1 is provided with a microphone 11 and a loudspeaker 13 for input of user speech and generation of audio signals for relaying to a user. An infra-red input/output port 12 is also provided to permit infrared optical data signals to be received from and/or transmitted to other mobile terminals which are also equipped with an appropriate port.
FIG. 2 is a schematic representation of key components of the terminal shown in FIG. 1. As shown, the terminal 1 includes a central control unit or processor 15 that, at least in general terms, is operable to control operation of the terminal. Coupled to the processor 15 is a radio unit 17 and timing control circuitry 19 that together are operable to control the transmission and reception of telecommunications signals to and from other telecommunications terminals or from telecommunications networks to which the terminal can connect via the aerial 5.
A removable data storage device or subscriber identity module (SIM) is provided for data and program storage. The data will usually comprise the IMSI (International Mobile Subscriber Identity) (which uniquely identifies the telephone), and other information such as a set of telephone numbers stored on the phone by the user. Software programs may also be stored on the SIM as part of the so-called SIM toolkit (or SIM application toolkit as it is otherwise known).
Coupled to the processor 15 is the display 3, and signals can be sent from the processor 15 to the display in order to convey messages, instructions, and other information to a user of the terminal. The processor is also coupled to the keypad 9 for data input by a user to the terminal.
Sound (for example user speech) picked up by the microphone 11 is processed by a speech processor 21 (for example to remove non-transmittable frequencies), and a coder/decoder (CODEC) 23 that is operable to convert analog signals generated by the microphone 11 into digital data for subsequent processing. The speech processor 21 and CODEC 23 are also operable to process received digital data and convert it into appropriate audio signals for relaying to a user by means of the loudspeaker 13.
Also coupled to the processor 15 is a ring generator 25 which is operable to generate one of a variety of different alerts which are used to alert a user of the terminal as to when a call, a message or other information is received at the terminal 1. In this particular case the ring generator is operable to generate appropriate signals to drive a vibrating buzzer 27, to illuminate an LED 28 (or bank of illumination devices) or to generate a ring signal for relay to the user via the loudspeaker 13. Typically, a user of the terminal is able to select which of these alert options are most preferable for their current ambient environment. For example, a user who is at work and does not want to disturb his or her colleagues with an audible ring tone might choose the vibrating buzzer as an alternative means to alert them to an arriving call at the terminal.
It is a recognised problem with communications terminals in general, and mobile telephones in particular, that it is relatively easy to accidentally place a telephone call to another party (a called party).
To combat this problem, most modem mobile telephones are provided with a “key lock” facility to temporarily disable the keypad of a mobile telephone (and hence prevent the user from placing a call until the keypad has been unlocked). However, it has recently been reported in an article published in The Guardian on Monday, 30 Jul. 2001, that despite the provision of such a facility, an estimated 24% of calls received by the emergency services in the United Kingdom (some 2,000 calls a day) were made from mobile telephones where no emergency service had been requested. These so-called “silent calls” were found, in the main, to have been made by mobile telephone owners who had made the call by accidentally pressing a key on their telephone.
Clearly, these previously proposed key pad locks are not providing a practical solution to the problem of accidental calls, and as a result these calls are still a significant nuisance to the emergency services and to users who are, of course, being charged for making the calls.
This problem of accidental calls is also not limited to the field of mobile telephony. For example, similar problems have been reported with landline telephone transceiver equipment (such as, for example, telephone equipment for direct connection to the PSTN) where the so-called “speed dial” facilities of modem wired telephone transceiver equipment have made it relatively easy (when cleaning the telephone equipment for example) to accidentally knock the receiver off-hook and inadvertently press a speed dial button. If this happens the telephone equipment automatically dials the stored number associated with the pressed button, and if the call is answered by the called party then a communications channel will be established between the calling party and the called party.
In the case of landline equipment, the problem can be exacerbated yet further by the particular design of PSTNs and associated telephony equipment which tends to keep communications channels open until the calling party replaces their receiver on-hook (hangs-up). This means that a called party who has received a silent call and has hung-up, can end up being reconnected to the silent call when they next pick up their receiver if the calling party has not hung-up in the meantime. When this happens it is often the case that the only way to terminate the communications channel is for the called party to contact the calling party by some other means (if indeed this is possible) and alert them to the fact that they have inadvertently placed a call.
A further problem that the present invention seeks to address is concerned with the situation where a calling party thinks that they have terminated a call (for example by pressing an end transmission button or by attempting to hang-up the receiver) but have in fact not actually terminated the call. In such circumstances the calling party could well find that the communications channel set up with the called party is kept open, and hence that they are still being charged for the call even though they think that the call has been terminated.
This problem is of particular significance in the field of mobile voice telephony given the relatively high cost of calls. It would also be a problem if a data call is initiated from a mobile terminal—for example, to a WAP (Wireless Application Protocol) gateway for access to the internet. In such a situation the WAP gateway would not take steps to terminate the call and thus a user who thought they had terminated the internet call but in fact had failed to do so would continue to be charged for the call until they realised that the channel was still open, and took steps to terminate it correctly.
In the field of landline telephony (for example via telephone equipment connected to a PSTN), this problem would be quite significant since the communications channel (as explained above) will tend to be kept open until the calling party hangs-up. Thus, a user who has placed a call and thinks that they have hung-up (but in fact have not correctly placed the receiver on-hook) would continue to be charged for the call until they realised that the channel was still open and took steps to hang-up properly.
It is an aim of the present invention to address, and preferably alleviate, the problems described above.